1. Field of Invention
The present invention relates to a touch sensor and driving method thereof, and more particularly to a dual-mode touch sensing apparatus and method thereof.
2. Description of Related Art
Regarding the developing of display technology, novel displays have been used in many types of portable device, such as a notebooks, a mobile phones, a digital camera and other electronic product. For avoiding these portable devices too heavy, the input apparatus have been changed from keyboards to touch panel.
Typically, three main sensing control technologies are used in touch panel including resistive touch sensing technology, electromagnetic touch sensing technology and capacitive touch sensing technology. According to the capacitive touch sensing technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed. The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel.
On the other hand, a sensor board using the electromagnetic sensing technology includes a substrate with an antenna array, a control circuit for calculating the touch position and a sensing pen. The sensing pen is a transceiver and the substrate with the antenna array is a receiver. When a user uses the sensing pen to touch the electronic paper display, magnetic flux is changed. A micro-controller can detect the change of the magnetic flux to calculate the touch position.
Typically, a touch panel using the capacitive touch sensing technology has those advantages including waterproof, anti scratch and high rate of transmission. Moreover, it is also very convenience for a user to use his finger to control this kind of touch panel. However, when a control point shown in the touch panel is very smaller than the size of human finger, it is very possible to touch other control point to trigger an unwanted function while a user uses his finger to touch this control point. Therefore, a new touch panel design that can provides different sensing supports is required.